Select the correct alternative(s)
    a) Elastic forces are always conservative
    b) Elastic forces are not always conservative
    c) Elastic forces are conservative only when Hooke's law is obeyed
    d) Elastic forces may be conservative even when Hooke's law is not obeyed

• A

   a, d

• B

  b,c

• C

  b,d

• D

  a,c